rust: Use variable to specify extra tools to install

All architectures may not support same set of tools, therefore use a
variable to specify this. E.g. on riscv32 rustfmt is not buildable
right now.

(From OE-Core rev: 332df9ebbd75a1825ac99abf1311d2e692d398d7)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/rust/rust_1.63.0.bb

@@ -56,13 +56,15 @@ rust_do_install:class-nativesdk() {
     rm ${D}${libdir}/rustlib/manifest*
 }
 
+EXTRA_TOOLS ?= "cargo-clippy clippy-driver rustfmt"
+EXTRA_TOOLS:remove:riscv32 = "rustfmt"
 rust_do_install:class-target() {
     export PSEUDO_UNLOAD=1
     rust_runx install
     unset PSEUDO_UNLOAD
 
     install -d ${D}${bindir}
-    for i in cargo-clippy clippy-driver rustfmt; do
+    for i in ${EXTRA_TOOLS}; do
         cp build/${RUST_BUILD_SYS}/stage2-tools/${RUST_HOST_SYS}/release/$i ${D}${bindir}
         chrpath -r "\$ORIGIN/../lib" ${D}${bindir}/$i
     done